This invention relates to novel bis-N-chloramides of aromatic and cycloaliphatic carboxylic acids and to methods for their preparation.
Bis-N-chloramides are valuable intermediate compounds, which, among other things, can be used for the preparation of diurethanes, di-ureas, diamines and diisocyanates. So far, only adipic, pimelic, suberic and sebacic acid-bis-N-chloramides have become known from German Pat. No. 909 455 and a publication by Eckert et al. in Rayon+Synthetics+Rayon Staple, 29, pp. 43-53 (1951) as aliphatic representatives of this class of substances. According to the processes described there, these compounds can be prepared with a yield of 37 to 95%.
On the other hand, no suitable process has been known so far for the preparation of aromatic bis-N-chloramides. Only U.S. Pat. No. 3,105,848 describes the preparation of isophthalic bis-N-chloramide by means of the chlorination of isophthalic acid amide. However, when this known process is worked, one obtains isophthalic acid-bis-N-chloramide only in a yield of 3.5% of the theory. Preparation according to this process of the isomeric terephthalic acid-bis-N-chloramide is not possible at all.
Only recently has it become possible to prepare the terephthalic acid-, as well as the isopthalic acid-bis-N-chloramide with a high yield according to a process described in Belgian Pat. No. 812 357. Cycloaliphatic and additional aromatic bis-N-chloramides have so far not become known.
Because of the importance of bis-N-chloramides as preliminary products for industrially important diisocyanates, there has existed a need to create additional compounds of this class substance.